DURING the 1928 presidential election campaign the Republicans circulated a rumor that if Al Smith, the Democratic party candidate, were to win the election, there would be a tunnel from the White House to the Papal Legation so that the Pope could control the United States. I am not sure that my mother actually believed in the tunnel story, but I remember hearing her talk about it, and I am sure that she voted Republican partly because Mr. Smith was a Roman Catholic and she, like most American Protestants of that era, was extremely suspicious of the Pope and of the things she imagined he might do to the United States if a Catholic ever got into the White House.
Since the economic boom of the '20s was still alive on election day of 1928, at least so far as most people yet realized, it is probable that Herbert Hoover would have won even without appealing to the anti-Catholic fears of the Protestant majority. But the Republicans were taking no chances and made the most of that anti-Catholic prejudice.
In other words, there is nothing unusual or unprecedented about the deliberate circulation of untrue or unfair or distorted rumors during a presidential campaign. The current floating of a false rumor about Michael Dukakis's mental health is surprising only because it was brought out so early in the campaign. The reason, however, is not difficult to identify.
Public opinion polls all seem to agree that American voters at this time seem to favor Governor Dukakis over Vice-President George Bush by about 17 percentage points. This is not a wide enough margin to produce a solid probability of a Democratic victory in November. Margins that great have been overcome before. But it is wide enough to make the Republicans face the serious possibility that after eight years in the White House, their tenure there can run out.
Parties facing such a possibility look around for any tool that may help them turn the polls around. Both Republicans and Democrats have black propaganda departments tucked away, unofficially and informally, in some back room of their headquarters. The use of theirs by the Republicans so soon, first noted by reporters during the Democratic convention in Atlanta, tells us that they are worried.
The Democrats had already attached the pejorative word ``wimp'' to the vice-president in current political parlance. The Republicans first retaliated with ``liberal,'' and now with ``invalid.''
This is an escalation in pejorative words. Both ``wimp'' and ``liberal'' are characterizations for which some evidence can be cited. There is no known basis for the suggestion that the lively, athletic, and emotionally secure Dukakis ever had a mental problem or psychiatric support.
We may presume that the Democrats are now looking for a response that can be as damaging. At a social gathering over the weekend I encountered two people who assumed there was substance behind the rumor. Both were surprised when I said there was no known evidence. So the rumor has done some damage to the Democrats.
It is a form of political warfare. It goes on in most American political campaigns, and in some others. British Tories have been notoriously ingenious at devising a ``bombshell'' for election eve.
Americans can expect more of the same before this 1988 campaign is over. There is no great ideological issue at stake. But there is one simple, practical political issue which is equally important to the warriors on both sides. For eight years the Republicans have been able to control the tax rates. If they lose the election, they lose control over tax rates.
Control of the tax rates is one way political parties reward their friends and punish their enemies. Plainly, the Republicans are not conceding the 1988 American presidential election - yet.